Aims: Systemic lupus erythematosus (SLE) is an autoimmune disease that can severely damage the kidneys, joints, and other tissues. Dietary interventions (e.g., antioxidant supplementation, manipulation of the fat content) can prolong survival in murine models of SLE. The role of these dietary factors in the etiology of SLE in humans has not been examined. Our study focuses on the role of dietary factors (antioxidants, fat content) in the etiology of SLE in humans. Accomplishments: I am collaborating with Drs. Walter Willett and Elizabeth Karlson on an investigation of dietary factors in SLE using the Nurses Health Study data, a cohort of 121,000 women ages 30-55 followed with biennial questionnaire assessment since 1976. Food frequency and nutritional supplement data were collected from 93,184 members of this cohort in 1980. Data on SLE occurrence were collected in 1982, 1984, 1986, 1992, and 1996. Our preliminary analyses of 57 cases diagnosed from 1980 through 1990 provided some support for a role of high intakes of vitamins C and E, but not vitamin A, as protective factors for developing SLE. Dr. Karlson recently reviewed medical records to identify and verify the 1990 - 1998 cases of SLE in the Nurses Health Study I cohort, and the 1991 - 1998 cases in a second cohort (Nurses Health Study II) that was initiated in 1989. This process has led to the addition of 58 new cases for our analysis, doubling the number of cases and significantly improving the statistical power.